1. Field of the Invention
The present invention relates generally to a process for manufacturing a cylinder liner forming the sliding wall of a piston in an internal combustion engine.
2. Description of the Prior Art
In a manufacturing process of this kind of the prior art, a thick cylinder is prepared of cast iron by a centrifugal casting method and is largely cut at its inner and outer circumferences-and at its end faces to form the cylinder and a flange wall on the outer circumferential portion at its one end. In another method using a steel pipe, the cylindrical tube is formed with the flange wall by folding one end of the tube outward.
In the former method of the prior art, however, a substantial material is cut at the inner and outer circumferences and so on to invite a drop of the yield, and there arises a problem of deteriorating the productivity. In the latter method, on the other hand, the width of the flange wall cannot be enlarged because the flange wall is formed by folding the cylinder outward, and the thickness is smaller at the flange wall than at the cylindrical tube body so that the flange wall has a tendency to have an insufficient mechanical strength. At the same time, the flange wall obtained is insufficient due to the fine cracking in the circumference thereof. Moreover, the cylindrical tube is liable to be bent inward at the folded portion or in the vicinity of the inner circumference of the cylindrical tube. This raises a problem that the portion in the vicinity of the inner circumferential portion has a tendency of being thinned by the subsequent honing step.